‘To build something 100 per cent in concrete is really intense. It’s like an inside-out building’
Fireproofing was an important part of the brief. ‘Every client is concerned about fire,’ says Casper. ‘We’ve seen fires in Scandinavia too, but California’s been on the extreme end, and the fire department says this is the new normal. It’s something the rest of the world will start thinking about too as climate change happens.’
As well as championing concrete’s staying power, the new building makes the most of the material’s low-maintenance nature. The exterior is rough, like the surface of rock, and comprised of lumber board-formed concrete, treated with a sealant but with no need for painting. Connecting the three volumes together into one continuous form, the roof is made of smooth-trowelled concrete slab, and unfolds its crisp, multi-gabled silhouette against the blue Californian sky.
Equipped to cope with nature and its vagaries, the retreat’s architecture is also deferential to them. Concrete floor plates are rooted into the side of the thin mountain ridge that climbs slowly from rolling valleys of cultivated vineyards, then peaks over a steep ravine. To accommodate a swimming pool and a plateau of garden space for the main house, the guest units had to be pushed right to the edge of the site, each stepped just over a foot down from its neighbour and cantilevered into the wild.
‘I’m a big believer in concrete after doing this project,’ says Casper, whose previous commissions were largely in wood. ‘Both for its sculptural qualities and its monolithic, permanent qualities. There’s also something elemental and honest and, in a strange way, quite natural about it.’ Adds Lexie, ‘The irony is that it is a simple material, but when you see the process that it takes to build something 100 per cent in concrete – from the formwork to burying every single cable and pipe – it’s really intense. It’s like an inside-out building.’
The pair cite European stone houses as a design reference. Yet perhaps even more than stone, concrete has an immovable quality and a reassuring heaviness in its solid poured form. The team lightened the load here, with two glazed façades and a neat square bathroom window on each unit.
Stepping in from beneath the Sonoma sun, guests are drawn into the refined concrete interior, made of a slimmer formwork. ‘We wanted everything to recede, so everything in the house, with the exception of the doors, was made of concrete,’ says Lexie. ‘We made the sinks out of concrete, the bathrooms don’t have tiles, and we painted the bath fixtures grey. Using solid pine doors, we added a little bit of warmth to where you would be touching the building.’
Once you’re inside this protective shell, nature draws you back out the other side towards the manzanita and pine trees beyond. The positioning of the guest house units to follow the topography of the ridge gave each one its own 180-degree panorama of the formidable landscape. ‘You get these open corners in each one of the rooms, which gives an amazing spatial quality and makes the rooms feel a lot bigger. Most importantly, they really open up to the view of the canyon, which is the most fantastic thing about the site,’ says Casper.